feat(config) implement enum check for properties

kong/tools/config_defaults.lua

@@ -9,7 +9,7 @@ return {
   ["proxy_port"] = {type = "number", default = 8000},
   ["proxy_ssl_port"] = {type = "number", default = 8443},
   ["admin_api_port"] = {type = "number", default = 8001},
-  ["dns_resolver"] = {type = "string", default = "dnsmasq"},
+  ["dns_resolver"] = {type = "string", default = "dnsmasq", enum = {"server", "dnsmasq"}},
   ["dns_resolvers_available"] = {
     type = "table",
     content = {
@@ -38,7 +38,7 @@ return {
           ["timeout"] = {type = "number", default = 1000},
           ["keyspace"] = {type = "string", default = "kong"},
           ["keepalive"] = {type = "number", default = 60000},
-          ["replication_strategy"] = {type = "string", default = "SimpleStrategy"},
+          ["replication_strategy"] = {type = "string", default = "SimpleStrategy", enum = {"SimpleStrategy", "NetworkTopologyStrategy"}},
           ["replication_factor"] = {type = "number", default = 1},
           ["data_centers"] = {type = "table", default = {}},
           ["ssl"] = {type = "boolean", default = false},

kong/tools/config_loader.lua

@@ -14,6 +14,24 @@ local function get_type(value, val_type)
   end
 end
 
+local checks = {
+  type = function(value, key_infos, value_type)
+    if value_type ~= key_infos.type then
+      return "must be a "..key_infos.type
+    end
+  end,
+  minimum = function(value, key_infos, value_type)
+    if value_type == "number" and key_infos.min ~= nil and value < key_infos.min then
+      return "must be greater than "..key_infos.min
+    end
+  end,
+  enum = function(value, key_infos, value_type)
+    if key_infos.enum ~= nil and not utils.table_contains(key_infos.enum, value) then
+      return string.format("must be one of: '%s'", table.concat(key_infos.enum, ", "))
+    end
+  end
+}
+
 local function validate_config_schema(config, config_schema)
   if not config_schema then config_schema = config_defaults end
   local errors, property
@@ -30,7 +48,6 @@ local function validate_config_schema(config, config_schema)
 
       local ok, s_errors = validate_config_schema(property, key_infos.content)
       if not ok then
-        --errors = utils.add_error(errors, config_key, s_errors)
         for s_k, s_v in pairs(s_errors) do
           errors = utils.add_error(errors, config_key.."."..s_k, s_v)
         end
@@ -40,13 +57,13 @@ local function validate_config_schema(config, config_schema)
     -- Nullable checking
     if property ~= nil and not key_infos.nullable then
       local property_type = get_type(property, key_infos.type)
-      -- Type checking
-      if property_type ~= key_infos.type then
-        errors = utils.add_error(errors, config_key, "must be a "..key_infos.type)
-      end
-      -- Min checking
-      if property_type == "number" and key_infos.min ~= nil and property < key_infos.min then
-        errors = utils.add_error(errors, config_key, "must be greater than "..key_infos.min)
+      local err
+      -- Individual checks
+      for _, check_fun in pairs(checks) do
+        err = check_fun(property, key_infos, property_type)
+        if err then
+          errors = utils.add_error(errors, config_key, err)
+        end
       end
     end
 

spec/unit/tools/config_loader_spec.lua

@@ -63,6 +63,17 @@ describe("Configuration validation", function()
     assert.False(ok)
     assert.equal("must be greater than 32", errors.memory_cache_size)
   end)
+  it("should check that the value is contained in `enum`", function()
+    local ok, errors = config.validate({
+      databases_available = {
+        cassandra = {
+          replication_strategy = "foo"
+        }
+      }
+    })
+    assert.False(ok)
+    assert.equal("must be one of: 'SimpleStrategy, NetworkTopologyStrategy'", errors["databases_available.cassandra.replication_strategy"])
+  end)
   it("should validate the selected database property", function()
     local ok, errors = config.validate({database = "foo"})
     assert.False(ok)